In relatively large chain saws, it is known to provide two oil pumps for lubricating the chain. One of the pumps is preferably positively driven by the motor. The second oil pump is provided in the event that a relatively large lubricating oil requirement should arise and is manually actuated by repeatedly moving an actuating lever back and forth to initiate pumping. This kind of redundancy in the oil supply apparatus is expensive. Operating the additional oil pump is also inconvenient, because of the need to move the actuating lever back and forth continuously while increased lubricating oil is required, and this affects the use of the chain saw.